Crystal Forms in Petrified Wood

December 09, 2022

TomMc_EPODImage2.WolverineLoopPetrifiedForest2022#2 (003)

TomMc_EPODImage1.PetrifiedWoodWolverineClose2022#1 (003)

Photographer: Thomas McGuire 

Summary Author: Thomas McGuire 


Grand Staircase National Monument is a spectacularly rich geologic area in remote southern Utah. Within this monument, Wolverine Petrified Forest, shown above at top, features silicified (petrified) tree trunks and sections. The variety of colors is caused by iron oxide and other oxide minerals.


In the bottom photo, the geometric forms at right are dark stained quartz crystals that probably grew by groundwater deposition in openings called “vugs.” Quartz is extremely common, but visible quartz crystals less so. When an igneous rock cools and crystallizes, quartz is the last common mineral to harden, so it usually fills in the irregular openings between previously formed minerals including feldspar, mica, amphibole and pyroxene. What surprised me was the texture on this exposed surface. The radial forms at the bottom of the photo are new to me, and I have yet to understand how they formed. Photos taken in July 2022.



Grand Staircase National Monument, Utah Coordinates: 37.799633, -111.214906

Related Links:

Petrified Forest of Northern Arizona

Smoky Mountain Graben, Utah

Spectacular Geological Offerings at the Cave Creek’s Rare Earth Gallery


Author’s Earth Science Books